The World's 20 Most Impressive Tunnels

Tunnels defy landscapes. By design they push away water, burrow through mountains, or simply encase the passenger in a protective shell from the outside. Tunnels provide passage in places that would be otherwise impassable. We searched low, deep, and under for the most impressive tunnels the cut through our world.

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Marmaray Tunnel, Turkey

Connecting Europe to Asia via tunnel was a nine-year process for the Turkish government. The Marmaray Tunnel—named after the Sea of Marmara that the tunnel runs through ("ray" means "rail" in Turkish)—is 47 miles long with a maximum depth of 180 feet. Opening in 2013, the Marmaray became the longest underwater tunnel in the world and gives Istanbul a new rail line in and out of the city. Crews used the immersed tube strategy to fabricate portions of the tunnel on the surface and then sink them and join them on the seabed instead of crunching through the solid rock of an earthquake zone. Flexible joints made of rubber-reinforced steel plates were designed to absorb any earth movement.

Eisenhower Tunnel, Colorado

At 11,013 feet, the Eisenhower is the highest vehicle tunnel in the world, at least according to Colorado's claims. Traversing the Continental Divide, the Eisenhower Tunnel complex moves through the Arapaho National Forest with two twin bores, both stretching just shy of 1.7 miles and at distances of 115 to 230 feet apart. Opened in the 1970s, the tunnels rise toward the west and at time can approach grades of 7 percent. Each tunnel comes in at 40 feet wide and 48 feet tall, but an exhaust and supply air system located above suspended porcelain enamel paneling in the ceiling creates a different visual for drivers.

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Gotthard Base Tunnel, Switzerland

We are mere months away from having a new world's longest and deepest rail tunnel. Construction has been going on for nearly 20 years, but the Gotthard Base Tunnel inside the Swiss Alps finally will open on June 1, 2016, moving rail cars of passengers and freight between Zurich, Switzerland, and Milan, Italy. At 35 miles long and dipping about 7,500 feet below the mountain peaks above it, the Gotthard Base Tunnel eliminates the need for winding mountainous routes by offering the first flat-track route through the Alps.

Seikan Tunnel, Japan

The current title holder of world's deepest and longest rail tunnel opened its 34-mile stretch in 1988 to eliminate the tricky storm-filled water passage across Japan's Tsugaru Strait. The tunnel goes down nearly 800 feet below sea level. The initial 1970s idea of using a tunnel-boring machine didn't work with the rock here. Instead, crews turned to dynamite to help carve out the needed space to successfully cart passengers from Honshu to Hokkaido.

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Tunnel of Love, Ukraine

This is no county fair ride. This 1.8-mile-long tree-encapsulated tunnel in the forests of Ukraine serves as a rail tunnel, moving timber to a factory near the town of Kleven. But the industrial run happens only a few times each day. The rest of the time this tunnel is a tourist draw, especially for the romantically inclined looking for a picturesque spot for a wedding proposal or even a simple kiss.

Channel Tunnel, United Kingdom/France

Impressive in scope, use, and engineering, the Chunnel stretches 31 miles under the English Channel, connecting the United Kingdom to France with what it actually a total of three tunnels. The six-year project created two 25-foot-wide tunnels for trains that run 365 days per year and reach speeds of nearly 100 miles per hour while a third tunnel exists as an emergency escape tunnel. Intricate systems of piston-operated air ducts and coolant pipes alleviate the pressure of the trains and the heat of the tracks. Traveling for 23 miles under the English Channel, the tunnel is one of the longest undersea passageways in the world, dipping to depths of 246 feet below the seabed.

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Bund Sightseeing Tunnel, China

Forget crazy engineering, historical significance, or world records. The Bund Sightseeing Tunnel in Shanghai has none of that. What is has is a dazzling view unlike any other tunnel on the list. The Bund Sightseeing Tunnel allows tourists to cross the Huangpu River in a 2,000-foot visually arresting experience with psychedelic lighting and blaring music.

Large Hadron Collider, France/Switzerland

At 17 miles in circumference and buried 570 feet below the France-Switzerland border, the Large Hardon Collider is a ring, not a tunnel from A to B. The enormous tunnel is a marvel of engineering in its own right, with engineers having to make everything absolutley perfect despite working deep under the Alps. Oh, and then there's that thing about discovering the Higgs Boson, one of the most important physics moments of the 21st century.

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Zion-Mount Carmel Tunnel, Utah

A century ago, the United States wanted to make its national parks more accessible—not an easy proposition back then for the parks in remote areas. To allow for direct access to Bryce Canyon and the Grand Canyon from Zion National Park, workers built a 24-mile-long highway through Zion, which includes the 1.1 mile Zion-Mount Carmel Tunnel, opened in July 1930 as the longest tunnel of its type in the country at the time.

It wasn't easy. Working in relatively soft sandstone, workers decided to create windows in the sides of the cliffs to remove the stone as they went. The softness also has required concrete reinforcement and a full-time electronic monitoring system that would alert park officials to any shift in the stone. Nowadays the tunnel is too small to handle two-way traffic of our oversized modern vehicles, so the typically one-way tunnel is managed during heavy tourist times, sometimes requiring long waits to enter.

Tokyo Bay Aqua Line, Japan

Instead of having drivers travel around Tokyo Bay in a 60-mile journey to connect the two industrial centers in the cities of Kawasaki and Kisarazu, the government built an 8.6-mile long bridge-tunnel hybrid, the Tokyo Bay Aqua Line, in 1997. A bridge runs to the manmade Umihotaru Island (yes, this tunnel has its own manmade island), where the roadway transitions into a tunnel that continues for the next six miles about 200 feet under the water.